Cellulose composition and process



Pasta May 19, 1925.

UNITED STATES 1,538,859 PATENT OFFICE.

wrnnuua G. LINDSAY, or NEWARK,

COMPANY, A CORPORATION OF NEW JERSEY.

I CELLULOSE COMPOSITION AND PROCESS.

No Drawing.

sustaining combustion, after the application of a flame at ordinary or normal temperature. This degree of non-inflammability will however, be varied according to desired conditions.

' I have discovered that inflammable materials which permit of a self sustaining combustion by the application of a flame at ordinary or normal temperature may be prevented from burning under ordinary conditions and rendered non-inflammable provided thereis present in suitable combination a heat absorbing compound capable of absorbing or taking up through decomposition, volatilization, or other change, all or the major part of the heat that would be necessary to raise the material or its components to the point at which ignition could be sustained.

This heat absorbing, or endothermic, substance or compound should be of such nature that it will decompose, or otherwise be in condition to absorb heat, before or when the temperature of combustion of the material to be rendered non-inflammable has been reached. The absorption of heat will thus proceed at such a rate as to prevent the combustible material from attaining its temperature of ignition. The endothermic substance or compound will also be selected having in view other characteristics besides its heat absorbing capacity bn decomposition in that it may be desired. to impart other properties to the resultant product. The relative proportions of the combustible substance, i. e., the substance to be rendered non-inflammable, and endothermic or heat absorbing substance, will be varied some- What to meet'conditions of strength, plasticity, transparency, or other desirable characteristics, butin general ;will b dependent upon the amount of decomposition,

Application filed April 24, 1922. Serial No. 556,311.

in heat unit equivalents, that can take place at or below the temperature at which combustion could be sustained by the exothermic compound if the heat of combustion were not absorbed at a greater rate than that at which it could be liberated. The

general rule is that a suflicient quantity of endothermic substance should be employed to absorb upon its decomposition, a sufliclent amount of. heat to prevent a sustained combustion of the said exothermic substance.

In carrying out my invention, any one of a number of products may be the aim. The characteristics of these from that of a hard. nonmoldable, dense solid sheet material which may be used for cutting out various objects such as brush backs, mirror backs, knife handles, etc., to that of a thin, highly flexible product which may be used for the veneering of fabrics, paper and the like or which can be used in place of varioustextiles and other flexible materials. The flexible compound may also be used as a substitute for leather. It may also possess the necessary characteristics required in compounds that are to be molded such as molded boxes, molded handles, molded brushes, mirrors, etc.

In carrying out the invention the procedure will vary according to the nature and physical properties of the material treated. The exothermic substance which I propose to use will be nitrocellulose, acetylcellulose, or some cellulosic ester, ether, derivative, or compound.

In the following examples I give such proportions as will be applicable to compounds containing nitrocellulose, as this is the most inflammable of the cellulose derivatives and any substance that may be incorproducts may vary NEW JERSEY, ASSIGNOR TO THE CELLULOID porated with the nitrate for the purpose of reducing, limiting or preventing combustion will be effective with other compounds of cellulose, and as a matter of fact, with cellulose itself.

-The permanent or nonvolatile solvents generally referred to as the plasticizing agents and which are to be combined with the yroxylin or other cellulose derivative for t e purpose of bringing about the necessary conversion, etc. in the course of manufacture, should be of such nature that the point of ignition is relatively high. In my experiments I have found that the organic Ill) - tion on the rolls.

. commercial grades phosphates possess the necessary characteristics of solubility and at the same time possess the requisite temperature of ignition. The most satisfactory results are produced with the aromatic phosphates because of their relatively high stability and resistance to decomposition, and because they possess at the same time the necessary solvent or plasticizing effect on the nitrocellulose, as well as a relatively high ignition point.

To a mixture of nitrocellulose and an aromatic phosphate. as for example, liquid tricresylphosphate, I add a suflicient amount of aluminum phosphate to prevent'the combined mixture from sustaining ignition upon the application and withdrawal of a flame; An example of proportions for this purpose is 100 parts of pyroxylin, 7 5

parts of liquid tricresylphosphate, and 125 parts of aluminum phosphate. Material of this composition, when manufactured according to the usual methods as obtain in the pyroxylin plastic industry, will possess hardness, toughness and moldability in similar degree to the usual varieties of celluloid, manufactured in the form of ivory, opaque colors and the like.

In the manufacture of these non-inflammable compounds I proceed substantially as in the manufacture of ordinary pyroxylin plastic materials incorporating the aluminum phosphate compound with the soaked or colloidized" mass of pyroxylin and liquid tricresyl phosphate prior to final mastication on the rolls. This incorporation may be effected in kneaders or the aluminum phosphate compound may be directly added during the course of mastica- The aluminum phosphate compound may also be incorporated with the proxylin in the same operation in which the liquid tricresyl phosphate is incorporated, the method for which is described in my U. S. Patent No. 1,233,374, granted July 17, 1917.

In the choice of liquid volatile solvent, I may select any one or a combination of a number of the common ordinary solvents, such as methyl alcohol, ethyl alcohol, acetic ether, acetone, amyl acetate, or the various and mixtures of these compounds as are ordinarily found upon the market.

In the manufacture of the flexible nominflammable compound having the properties of leather and the like, I proceed as in the example specified but instead of employing phate.

method for the manufacture of pyroxlin plastic compounds and produced in the form of sheets by shaving from a block, or itmay be dissolved in a suitable proportion of solvent such as wood alcohol, acetone and the like and spread upon a suitable surface such as a textile fabric, leather and the like.

, I claim 1. A composition of reduced inflammability containing a cellulose ester and an a-romatic phosphate and in close association therewith aluminum phosphate.

2. A composition of reduced inflammability containing a cellulose ester and aluminum phosphate.

3. A composition of reduced inflammability containing a cellulose ester and tricresylphosphate in admixture with aluminum phosphate.

4. A composition of reduced infiammability containing pyroxlin and aluminum phos- 5. A ity containing pyroxylin, an aromatic phosphate, and alummum phosphate.

6. A composition of reduced inflammability containing pyroxlin tricresylphosphate and aluminum phosphate.

7. The rocess which consists in mixing liquid tricresylphosphate and aluminum phosphate with hydrous pyroxylin.

' 8. The rocess which consists in mixing liquid tricresylphosphate and aluminum phosphate with hydrous pyroxylin, and manipulating the mixture in the presence of-a volatile solvent.

9. A composition having substantially the physical properties of the usual pyroxylin plastics and comprising a combustible organic ingredient and a fire retarding ingredient, said latter ingredient consisting of aluminum phosphate.

10. A tough non-inflammable cellulose composition containing aluminum phosphate in excess of 25 per cent of said composition.

11. A tough non-inflammable cellulose composition comprising a fire retarding ingredient in excess of 25% of said composition, sald fire retarding ingredient comprising aluminum phosphate.

WILLIAM G. LINDSAY.

composition of reduced inflammabil- 

